Possible Clues:

• Marshall Islands, e.g.
• Spots for snorkeling
• Components of the Maldives
• Lagoons' surroundings
• Is that what one has to pay to go on the roads to the isles?
• Rings of coral islands
• A lot of Oceania
• A levy is charged to get to the islands
• Enewetak and Kwajalein
• Islands that form atop underwater volcanoes